


If You're Gasoline, I'm Matchsticks

by an_aphorism



Category: Voltron: Legendary Defender
Genre: Alpha Shiro (Voltron), Alpha/Beta/Omega Dynamics, Anal Sex, M/M, Mating Cycles/In Heat, Omega Keith (Voltron), Pining, Pre-Kerberos Mission, Scent Kink, Scenting, Shiro is a Mess, Teasing, helping with a heat, you know platonically
Language: English
Status: Completed
Published: 2019-10-02
Updated: 2019-10-02
Packaged: 2020-11-22 04:55:32
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 6,418
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/20868536
Author URL: https://archiveofourown.org/users/an_aphorism/pseuds/an_aphorism
Summary: But being attached at the hip means that Keith is there when omegas come up and flirt with Shiro, when they brush up against him and ask him to walk them to their rooms. He’s there and he sees it all and it clearly gives him an idea—Or: Shiro is a good alpha who helps omegas in heat by allowing them to platonically scent him. This goes great for him until Keith.





	If You're Gasoline, I'm Matchsticks

**Author's Note:**

> AMAB language used for omega!Keith, his parts are left vague.
> 
> Set pre-kerb, but as an AU no ages are specified.

Shiro tries to be a good alpha, and in the end it’s not really all that difficult. His parents taught him to treat everyone with respect, and to be even gentler with omegas. He knows the alpha stereotypes, and he knows they don’t exist for nothing. There _are _alphas out there acting like complete knothead assholes. Shiro wants to do his best to make up for those people in any way he can.

So he’s aware of his size, of the stature he has just by birth. He’s always aware of an omega walking all alone, and he does his best to hang back, to cross to the other side of the street. Shiro never approaches or makes comments to omegas, and when they do interact with him he makes sure to lower his shoulders, leave an opening for them to leave if they need to. He absolutely does not touch them without verbal consent.

It’s not hard. By the time Shiro gets to the Garrison he hardly even thinks about it. It’s just the way he acts.

Respectful. 

But Shiro would have to be blind to the amount of attention he gets for it. Omegas _flock_ to him, asking him to walk them home, to study with him, to help them with things that require an alpha’s strength. It incites Shiro at first, that such basic decency makes him _popular. _It disgusts him that so many omegas haven’t been treated right, that they see him and idolize him.

Because Shiro’s not doing anything special, or even anything that’s _hard. _He’s just aware of his privilege, aware of society, aware of history.

It does shift his priorities though. If he’s going to be the bar, then he really wants to set it. He wants to shame every other alpha these omegas have come in contact with so maybe they too will step it up.

He wants to rewrite how alphas should act to the omegas he encounters, so that they won’t settle for less than the bare minimum.

“I heard them again in the locker room,” Matt says sitting down with his lunch tray beside Shiro. “They’re counting down the days until you graduate.”

Shiro rolls his eyes. He’s famously unpopular with some alphas at the Garrison, but it’s not Shiro’s fault that omegas are finally understanding that they don’t have to put up with bullshit. It’s not his fault that other alphas aren’t _better. _

“Just wait until they hear I’m up for a teaching position,” Shiro says.

Matt grins, reaching for Shiro’s banana to switch it for his apple. “Honestly I can’t wait.”

##

When Shiro gets the teaching position, it gets somehow worse. Shiro doesn’t know what it is, but the position of more authority means he suddenly starts getting requests for scenting or sharing a heat.

He’s older and in higher ranking than most of the omegas around, so sex isn’t a good idea.

But he knows from his family how it is for an omega to get through their heat alone, so Shiro says yes to requests for scenting.

It’s easy all things considered. Most of them just get near enough to sniff his scent gland and stand there for a few minutes. Shiro watches as they relax, as the quivering heat fades to a more comfortable burn. When they’re finished they smile at him a little dopily, and then Shiro walks them back to their rooms.

He can’t in good conscious leave an omega in public in that condition.

Some omegas are more ambitious though. Some cuddle up to his side or sit down on his lap and nuzzle at his scent gland. Shiro doesn’t mind that either. The bodily contact is nice and being helpful is it’s own reward.

And Shiro’s had enough contact with omegas in his life that this isn’t that weird, and it certainly isn’t arousing. It’s just like any other helpful task.

The problem with his set up, though, appears one summer day in the form of a slender raven haired omega who first blows his sim score out of the water, and then steals Shiro’s car.

It’s surprising and interesting, to say the least.

##

There’s really nothing different about Keith, except that Shiro can’t keep away from him. After getting Keith into the Garrison, Shiro finds every flimsy excuse to stop by his dorm or find him at lunch or after classes.

It’s helpful in the way that Keith, when he first arrives, is turbulent and defensive bordering on violent. Shiro’s seen the type before, and knows better than the senior professors that punishment and derision is not the way to make progress with him.

instead, Shiro meets Keith’s bristling attitude with compassion, clever snark, and some recklessness on a hover bike. It works a little too well.

Before Shiro even knows it they're friends, good friends. It's the easiest friendship Shiro's ever made.

But being attached at the hip means that Keith is there when omegas come up and flirt with Shiro, when they brush up against him and ask him to walk them to their rooms. He’s there and he sees it all and it clearly gives him an idea—

Not that it’s wrong or bad. Because Shiro _does_ help the other omegas and does so cheerfully and without nefarious motive. It’s just… when Keith starts the same behaviors... it hits a lot different.

##

The first boundary transgressed is a small one. Keith puts a hand on Shiro’s shoulder to look over at the sim screen as it’s doing a replay. It’s a student’s run that Shiro is supposed to be analyzing, but the second that warmth and smell hits Shiro, he’s useless.

It’s just that Keith is _so_ guarded, his physical touches so carefully doled out. That’s why Shiro notices. At least that’s what he tells himself.

But then it’s lunch, the space between them disappearing, Keith right up in his space as they share stories and lunch foods. It's later in the evenings when they go out on the hover bikes but Keith asks to take one because he likes to enjoy Shiro’s piloting.

And it's when they sneak back in after curfew Keith and leans up against the bike and gives Shiro a shy,_ walk me back to my room?_

Shiro is powerless to fight the pull. The first time Shiro walks him back to his room is both the longest and shortest walk of his life. Keith is bright-eyed and wind-blown after the ride, and Shiro can’t stop sneaking looks. He’s sure he isn’t subtle, but they chat quietly and Keith doesn’t mention it.

Shiro can’t stop thinking of Keith's warmth though, pressed against his back. Those strong arms banded around his waist. Even the way Keith had gasped and whooped as they took hard corners and sharp dips has him feeling a little faint.

When Keith opens his door and turns back to bid Shiro goodnight, Shiro’s struck by how date-like the evening was. How Keith is standing in the dim light of his doorway, looking up at Shiro with a small smile.

“Goodnight Keith,” Shiro says. He keeps his eyes on Keith’s face and does not for any reason let them move to the room beyond. To the implication of. 

“Goodnight Shiro,” Keith says, so soft in the quiet. He looks up through his eyelashes and it’s—

_Stars._

Only when Keith turns away does Shiro realize that he’s leaning against the doorway, one hand clasped over the open edge. He’s doing that thing he’s chided many an alpha about.

It’s shameful how difficult it is to pull his hand off the edge and let the door slide shut.

His last view of Keith is him looking back over his shoulder, a smile on the edge of his mouth.

Shiro stalks back to his room and straight into a cold shower. He mourns the loss of Keith’s scent even as he scrubs aggressively at it.

Lying in bed that night he does not think about it.

##

It gets worse.

(Better.)

The hand on his shoulder becomes a hand on his arm and then becomes movies on Shiro’s couch where Keith falls asleep leaned up against him. Shiro absolutely does not use the word _cuddle_, because if it were any other omega Shiro wouldn’t even think it. Keith deserves the same respect.

But _fuck_ is it difficult to remain objective. Keith curled up against him looks so peaceful and calm and beaut—

And the smell. Shiro’s never smelled an omega like him. There’s something about it that just gets in his head and he can’t shake it. It only makes Shiro wonder about how good it would be from the source. If he could put his nose to the scent gland on Keith’s neck and just—

Shiro has to adjust his pants and then spend ten minutes thinking of every foul and embarrassing thing in his life. When he’s decent again he gently wakes Keith and then walks him back to his room.

The soft, rumpled look the omega has as he bids Shiro goodnight at the door haunts Shiro for the next week.

##

Next to ruin Shiro's life is the sparring. What began as a way to channel Keith’s energy and aggression slowly becomes torture for Shiro. Keith comes into the gym in _painted on_ leggings, turning more than a few heads.

And he spars just as well as he pilots. Agile with his speed, Shiro has to bring his A-game to keep up, and even then Shiro still gets caught by a sharp smile or the curve of Keith’s hip as it moves around him.

That’s to say nothing of what it’s like when they get down on the mat. Shiro knew it would be… challenging when he pinned Keith, but the reality is striking.

On the mat Keith is breathing hard and glistening with sweat, but he’s absolutely radiant. Shiro towers over him and for a dizzying moment the scene shifts to something different.

His omega beneath him, gasping and begging for—

Shiro gets up too quickly, slamming the door shut on that line of thinking.

Every sparring session after is a practice in self control that leaves Shiro in the cold shower afterwards, washing off the scent so he won’t do anything untoward.

##

None of that though prepares Shiro for the day that Keith shows up at his door smelling of an omega in early heat.

Shiro’s first thought is of panic. His rational brain begs him to slam the door shut.

But Shiro can’t do that to Keith. Keith’s his friend.

At least that’s the reason he tells himself that he doesn’t immediately turn Keith away.

“Hey Keith,” Shiro says instead.

“Hey,” Keith is flushed, dressed down in leggings and a tee shirt. Likely he’s been medically excused from his classes for the next few days. “So uh.”

Keith stops then, uncharacteristically shy. Shiro hasn’t seen the shyness since their early interactions, it raises alarm bells.

“Is everything okay?”

“Yeah,” Keith says. “Well,” he waves a hand casually, “you know. So I know you’ve helped other omegas and I was wondering…”

It doesn’t take anything more for Shiro to get it.

Of course Keith would ask, should ask for his help. They’re friends and Shiro is widely known to help out omegas. It’s the logical conclusion. He can’t turn Keith away, even if he should, because how would he explain it? 

Plus Shiro would rather Keith come to him than any other alpha. Just the idea of it burns violently in the back of his throat.

Shiro opens the door. “Oh yeah, Keith, of course.” His voice sounds deceptively normal.

But this is normal. Alphas help omegas all the time with stuff like this and it's fine. It’s only Shiro who’s breathing in Keith’s delicious heat scent and getting off track. It’s only Shiro who’s doing something aberrant.

Still, Keith smiles and comes inside, the anxiety falling away. Shiro can’t help but feel proud of that.

And if he has to suffer through this, then that’s fine. Anything for Keith.

“It just sucks, you know?” Keith starts as they make their way to the living room. “Suppressants are great but you still have to have a heat at least once a year. Went to get my pills and I hadn’t scheduled a heat this year yet so they held the meds. Didn’t think about the timing right before finals. Stupid.”

“I’m sure you’ll still do great,” Shiro says because he doesn’t want to touch the subject of Keith’s heat if he can avoid it. What they’re about to do will be more than enough.

“Yeah,” Keith sighs and crosses his arms, standing beside the couch. “It’s still stupid though. Don’t see why I couldn’t skip a heat once in a while.”

Shiro takes the lead and sits down. “It’s not healthy,” he says, looking anywhere but at Keith.

“Yeah yeah,” Keith snarks, and then instead of sitting next to him like Shiro expects, he plops down on Shiro’s lap.

“Oh!” Shiro’s hands come up immediately to Keith’s hips, alarm in every stiff muscle of his body.

“Is this okay?” Keith asks. He’s looking down, a little unsure.

Shiro squeezes one of his hips and then _immediately_ regrets it. “Y—Yeah,” he swallows hard.

Keith is heavy and warm and _sitting on Shiro’s lap. _Shiro rolls through a handful of embarrassing memories, but can’t scrub out the way his hands feel cupping those slender hips.

“Cool,” Keith says and then adjusts so he’s straddling Shiro, arms over Shiro’s shoulder. “I’ll be quick.”

When he leans in Shiro tries not to breathe, but it’s near impossible. Keith’s scent is thick and everywhere, and as he leans in to Shiro’s throat, his own scent gland is offered.

Shiro’s eyes go right to it, his hands tightening on Keith’s hips. He’s never scented an omega that wasn’t family, never even wanted to.

But _stars_ how he wants now.

Keith leans right against his chest and buries his nose in Shiro’s neck. Shiro moves his hands back around Keith like a hug.

It’s exactly what he does for omegas who get right in his space. They’re often looking for comfort, to be held while they calm down.

But tightening his arms around Keith makes Shiro’s belly flutter. That, and the ticklish sensation against his throat before Keith starts nuzzling.

He tells himself to get a grip, but he’s slipping fast. Keith smell is everywhere, heavy and teasing. It spreads as Keith nuzzles his neck.

Keith makes a low hum sound, and Shiro starts to rub his back. It’s automatic, his body going on and doing the right thing even as he’s freaking out.

A few seconds go by. Shiro breathes and soothes and wrangles his own inappropriate thoughts. He’s almost got them in hand when Keith shifts again and scatters all his best intentions to the wind.

Then Keith starts licking him.

It’s not unusual for an omega, but it’s also not common, especially with the kind of exchanges Shiro does. What he does isn’t personal and for the most part omegas respect that. Shiro should have known better with Keith though. Keith and he are _familiar_. Friends. So Keith wouldn’t think twice about holding back. Maybe he doesn’t even know that he should.

The correction is on his tongue, but Shiro swallows it. He should stop this, but he doesn’t want to. He likes that Keith feels so comfortable with him, that he feels like he can do this.

And quickly Shiro is losing all sense of right and wrong. He’s hard in his jeans and Keith smells like a fucking dream. 

Shiro tries, he really does, but Keith is just too powerful. Every time Shiro thinks he’s gotten his head out of the gutter Keith will do something to drag him right back down.

He sucks and licks at Shiro’s scent gland, his body pressing hard to Shiro’s and then relaxing. Pressing and relaxing.

And before Shiro even realizes it, they’re doing a gentle rock. Not a _grind, _absolutely not that.

Just.

Rocking.

It’s fine. Good. _Fuck._

Keith settles in against his throat, hips moving against Shiro’s. It’s hard to tell if he even knows he’s doing it. He probably doesn’t. An omega's heat can be inebriating. It can make them act in ways they wouldn’t otherwise, and is often the reason alphas think they can get away with inappropriate shit.

Shiro holds on tight to that. He won’t be that person, won’t act upon Keith when he’s like this. Omegas are more than just a knothole.

But then Keith starts purring, and Shiro almost loses himself. His hands tighten on Keith’s hips, and instead of just holding, he finds he’s subtly guiding. Moving Keith on his cock just for a little _friction—_

Fuck. Fuck. He needs air. Needs space. Needs to get his mouth on that sweet smelling gland, his knot stuffed in—

Shiro bites his lip hard to try and sober himself up. He can’t be getting off on this, this is practically a healthcare service.

Keith is just so…

He fits just right on Shiro’s lap, tucked up against his throat. Better than any other omega ever has, and due to Shiro’s helpfulness he’s certainly had quite a few.

None of them have smelled like Keith. Smokey and spicy, it reminds Shiro of gasoline. Not the _smell_ per-say, but that animal-brain sense he gets when he smells gasoline. How he likes it but he doesn’t know why, or how such an harsh smell could be _pleasant_.

Because Keith’s smell is. Pleasant. Deeply. Obsessively.

And it’s all for Shiro. They’re alone in his rooms, and Keith is displaying so beautifully for him. Throat bared as he snuffs and croons into Shiro’s gland. He’s perfect and he’s all Shiro’s. _Shiro’s omega._

His cock throbs as he starts to move his omega harder on his lap. It’s good, so good. Would be better without all this clothing.

He can smell it, his omegas tight little hole. He just needs to get this cloth out of the way— then he can—

The smell and warmth rips away from Shiro so fast then that it’s dizzying.

He blinks stupidly up at Keith who’s standing, gently smiling at him.

“That was really helpful,” Keith says. “Thanks, Shiro.”

Shiro blinks and blinks and then some fresh air must finally hit his brain because he _remembers_.

This was not a mating, Keith is not his omega, and Shiro almost—

If he weren’t still so turned on the shame would be crushing. Or rather, maybe if Keith seemed troubled at all Shiro would feel more presently guilty.

But Keith looks a little dazed as omegas do after scenting, but he’s already moving toward the door, seemingly unaware of Shiro’s transgression.

Shiro should get up and walk him back, but he’s so hard that sounds like an impossible task. Anyway Keith is at the door now waving him farewell. “See you on the other side,” he grins cheekily at Shiro, and then is gone.

There’s a beat of absolute silence and then Shiro can’t help himself, he scrambles to undo his pants.

The first stroke on his cock is sublime. It’s wet and hot and he’s already halfway to a knot. He doesn’t even try to fight the visions that come.

But it’s less than it could have been. Shiro strokes himself but already the scent is fading, the memory of heat and weight on his lap not as good as the real thing.

If only he had something with Keith’s scent, something he could—

The idea that pops into his head is absolutely filthy, but he’s so desperate he doesn’t even hesitate. Quickly he fumbles to get his pants off, and then drags it up to his face. Shiro presses his nose to the front where Keith was sitting— grinding— himself.

It’s not like the real thing, but there’s a slight remnant. The smell of Keith’s slick.

Shiro breathes it in like a madman, his hand stroking hard, grunting as his knot is tricked to swelling by the faint scent of omega in heat.

It feels amazing and he still knows it pales in comparison to the real thing. Keith would be so hot and wet on his cock, whining and desperate, begging for his knot.

The thought tips him over, pleasure sparking down through his belly. Shiro growls and strokes his cock, coming heavy and slick all over his jeans, biting and sucking at the fabric just to get the slightest taste. It goes on and on until he’s finished, completely brainless.

Slumped on the couch filthy and trying to catch his breath, Shiro knows he’s completely fucked.

##

Keith’s next heat is in a lot of ways significantly worse. For one, Shiro knows it’s coming, and for another, he’s so deeply, deeply fallen for the man.

Because it’s been almost another year. Another year and Keith is older, wiser, and infinitely more beautiful. Another year and Shiro’s so inexplicably lost on him, for who he is on the inside as well as the outside.

In the last year they’ve cried in front of one another, shared their hopes and fears. They’ve made plans for what they want to do after the Garrison. It was all _as friends_ of course, but every little thing about Keith is like a hook snagging on Shiro's tender heart.

So Shiro knows the knock when it comes. He knows even before he answers the door what it’s about.

Matt just a month earlier made a bet with his little sister that Keith’s heat this year would be Shiro’s undoing. They'd spent an entire lunch period teasing him about his impending demise while Keith wasn't there. But Shiro hopes he’s stronger than that. Surely everything he preaches about alpha manners is not him just blathering on. He has to be good enough for Keith, he won’t disappoint him by being inappropriate.

Shiro takes a deep, centering breath, and opens the door. Keith on the other side would be like any other day, except this time the shyness is back. He’s looking over Shiro’s shoulder instead of directly at him.

It’s a déjà vu of the worst kind. It takes Shiro right back to last time. Reminds him of how torturous and wonderful the whole thing had been.

Shiro’s orgasm had been _good,_ and he’s still using the memory of it to get off every so often. He shouldn’t, maybe, but he’s only so strong.

And it’s become so commonplace in his life that it doesn’t even distract him anymore. His fantasies of Keith and Keith in real life are separate. Shiro’s good at compartmentalizing. He’s in love with Keith, and that’s a simple, clean fact, there’s no need to dwell on it. There’s certainly no need to bring it into their friendship when it’s running so smoothly.

Keith bats those delicate eyelashes up at him, cheeks pink as he makes his request. He looks good enough to eat.

Shiro doesn’t know what he says, but it must be normal enough because then Keith is coming in his apartment.

Shiro swallows and tries to think about the reports he needs to finish by the end of the week, about mac and cheese the cafeteria made last week that had way too much dairy and upset his stomach for a whole day.

It’s only minimally successful, because then he’s sitting on his couch and Keith’s crawling up onto his lap.

When Shiro’s hands fall on his hips this time he notices the change. It’s not much, but Keith’s hips are definitely wider, a slightly more attractive curve against his slender waist. He’s still masculine, the wider cut of his shoulders say so, but the change catches Shiro right in the chest.

“Is this okay?” Keith settles into the same position as before, straddling Shiro, arms around his shoulders.

“Uh huh.”

Shiro bites his lip when Keith then scoots closer, sliding his ass across where Shiro is already getting hard.

Hot breath tickles his throat as Keith presses his nose to scent. “I always forget how good you smell,” Keith says with a sigh.

There’s no trusting what Shiro will say if he opens his mouth, so he hums a neutral sound behind clenched teeth. It’s enough for Keith who starts nuzzling his neck.

Shiro wraps his hands around Keith as the man collapses further into him. He’s a good weight now, and warm from the oncoming heat.

_Stars, _how Shiro wishes he could keep him.

The nuzzling goes on for a little while longer and Shiro takes to smoothing a hand up and down his back. He tries to ground himself with the action, and remind himself that he is a caregiver.

When Keith starts licking at his scent gland, Shiro’s cock throbs to remind him he’s also a pervert.

Or, to be more kind to himself, he’s a man who doesn’t have any defenses left against those breathy sounds that Keith makes. Especially when they start to come with that slight rocking he does.

Shiro’s hands move back to his waist. He means to stop Keith, to hold him in place—

He can’t. Keith’s smell is once again filling his lungs and making him hazy. He knows it’s bad to let Keith lick and suck and grind on his lap, but it feels so good he can’t quite remember _why_ it's bad.

“Sh…” Keith sucks at his neck, smearing the syllables into his skin.

Shiro’s hands tighten on Keith’s waist. “Hm?”

No answer comes and Shiro forgets it in the heat that’s being stoked between them. In the gentle rock that is rolling into something more.

Shiro opens his eyes that he doesn’t remember closing, and sees Keith’s throat just before him. There’s an attractive pink flush there that Shiro just wants to put his mouth on. Keith’s claws scrape at the back of his neck, pulling him in, and that’s all the invitation Shiro needs.

He presses his mouth and nose to that beautiful curve and inhales the scent of Keith’s oncoming heat. The memories have nothing on the real thing. He’s _delicious. _

“_Ah, Shiro,_” Keith’s nail dig in harder, his sucking kisses burning up and down Shiro’s throat.

“Keith,” he groans into his skin. He licks and sucks and is just about to bite—

A huge red flashing warning breaks through his mental fog. A bite? He can’t bite Keith… Keith isn’t his…!

Shiro tears his mouth away with a gasp.

“Fuck, fuck, I’m sorry—“ Shiro tries to push away, to make some space for the air to douse them. Keith denies him this, clinging tightly, face hidden against Shiro’s throat.

“No, it’s fine. Don’t— I need—“

“It’s not fine.” Shiro’s heart is pounding, and the smell keeps threatening to pull him under. “Keith…”

Keith whines, holding him tightly.

There’s nothing else for it. Shiro’s cornered himself, shown his hand. The least he can do now is be honest so Keith doesn’t take it as a rejection when he’s in such a fragile state. “Keith,” he swallows hard, takes his hands off those hips. “Keith, I’ve lost objectivity.”

“What?”

Shiro doesn’t know how Keith could possibly miss the very inappropriate hardness right beneath him. “Keith I’m… compromised. I can’t do this for you anymore.”

This gets Keith to sit back and look at him. Shiro’s breath catches at the sight of him. Keith’s a _vision. _

His lips are red and wet, matching the pretty flush across his cheeks. Those gorgeous eyes are huge and dark, a little soft in the heat haze.

Then he frowns. “You can’t…?” He doesn’t say it, but Shiro can see the moment that Keith turns it in on himself. His rough upbringing has taught him that way of coping, and it’s heartbreaking to witness.

“Keith, no.” He cups Keith’s face, one thumb smoothing the sharp angle of his cheek. “It’s not you. You haven’t done anything wrong. It’s—“

And then maybe because Shiro would do anything to spare Keith harm, he decides to throw himself under the bus. He shifts his hips pointedly.

“It’s uh. I— I like you. A lot. Too much. I’ve lost all ability to do this without—“ Shiro clears his throat. “And I know it’s inappropriate and I’m sorry, I really thought I could handle it. I’m always trying to be a decent alpha, but I’ve messed up here and you deserve better, I’m sorry.”

He could go rambling on, but it’s more than enough. Shiro snaps his mouth shut.

There’s a beat of silence and then Keith laughs in his face.

The man is arched back, mouth split wide in amusement. Shiro’s completely baffled.

“Oh _stars_, I should’ve known,” Keith looks him over and then shakes his head fondly.

“What?”

Keith’s still smiling when he leans in and drops a kiss to the corner of Shiro’s mouth. “In all your goodness and honor, did it ever for one second occur to you that maybe I was _interested?_”

Shiro’s head stumbles over that implication. “What?” He says again stupidly.

“Uh huh. I like you too. Have liked you. Thought that was clear the last time we did this.”

“What?” And then because he can’t just keep babbling the same thing over and over again. “How? I— how was I supposed to know that…?”

“Why else would I come to you for this?”

“I help lots of other omegas!”

Keith wrinkles his nose in distaste. “Well you won’t be doing that anymore.”

Shiro blinks and blinks at him.

“So,” Keith’s hands curl pleasantly around his neck. “Can we get back to it then?”

“But—“ Shiro’s still reeling. “But you’re almost in heat.”

Keith tilts his head at him. “Uh huh, that’s kind of the point.”

“But you’re…” Keith raises an eyebrow at him. “Compromised.”

The full Keith smirk blooms them. “Maybe I’m a little more out of it than usual. But do I really seem unable to consent to you?”

And now that Shiro really thinks about it, Keith surely is more with it than he is in this moment. “No, I guess not.”

Keith nods and shifts on Shiro’s lap to make him gasp. “Any more arguments then?”

Nothing comes to mind. Absolutely nothing. His hands slide down Keith’s body of their own will. “No.”

Keith’s close then, lips parted on offer. “Good,” he whispers.

Shiro never stood a chance. He pulls Keith in the rest of the way and kisses him.

It’s like their momentum never faltered. Keith opens for him and it’s all Shiro can do to follow, to lick into his mouth and taste him. It’s hot but it also gets his heart tumbling. He feels excited, like electricity is tingling along all his nerves. Like he can’t get enough.

He grabs and pulls and kisses Keith. Works his way from his mouth to his throat only to go back again at the first moan that drops from Keith’s lips.

“_Shiro_,” Keith whines into his mouth. It tastes delicious. It tasted like the only thing Shiro wants to dine on forever.

Keith grinds on his lap, helped by Shiro’s hands to get him just right.

It’s good, but it’s quickly becoming not enough. They’re a feedback loop and it’s winding tighter, the smell of Keith’s heat swamping the room. Shiro licks the scent off his mouth and his throat and starts plucking at his clothing. He wants, _wants—_

They’re falling too fast for words, so those go. Instead as if by agreement they’re unbuttoning and tugging off clothing. Shiro grabs at all the new skin, driven half mad by how _much_ there is. And they still haven’t even gotten their pants completely off.

Keith has to slide off his lap for that, and they both fumble furiously with their own clothing. The relief as Shiro frees his cock from his pants is worth it.

It’s even more worth it when Keith slides back onto his lap utterly bare and panting. The heat of him brushes against Shiro’s cock, his own hard cock smears wetness on Shiro's stomach.

Keith whines and claws Shiro in closer, getting his mouth on his scent gland and then his lips. They kiss messy, too much saliva and a clash of teeth. It’s devolving just into need, into the bristling aggression of Keith’s heat.

There will be no stopping soon. Maybe even now. Shiro can hardly hold a thought beside, _Keith, Keith. _He pulls his mouth away to ask, maybe to double check, but the words never make it.

Keith advances on him and bites at his mouth, growls and takes one of Shiro’s hands and guides it back and down. The fingers touch heat, slick. Shiro growls and then plunges his fingers in.

Keith yowls, arching to get his finger deeper. He’s nearly dripping. Impossibly hot around Shiro’s finger.

_Fuck. _

Shiro’s cock is painfully demanding. All his alpha senses know what happens next. The omega is primed and ready and crying out to be taken. His wet hole is practically rubbing the length of Shiro’s cock. It would just take a small adjustment.

Keith lifts up the same time that Shiro gets his other hand on his cock. The man comes down just right, absolutely perfect, and Shiro’s cock slides inside him.

Keith’s body is made to take an alpha knot, but he’s still small and tight— Shiro hisses at how he squeezes him. He doesn’t want to come so soon, but his omega is making that difficult.

Keith bites at his throat, mumbling half words of encouragement. Shiro responds in kind, dragging his teeth against the tender skin of the omegas throat. It’s absolute bliss.

“Alpha,” his omega says.

The word sizzles down Shiro’s spine and then he’s clutching those hips tight and beginning to move him. Lifting his omega with ease and pulling him down completely on his cock.

The scent is near choking and Shiro wishes that he had spared a moment to taste it. Although, maybe that will be the treat for after. After he’s knotted Keith full he can spend the afterglow between his legs lapping up what spills out.

It drives him mad. He fucks hard into Keith, spurned on by the smell and heat and beautiful cries spilling from Keith’s lips. 

Keith seems equally as out of it. He moans and whines and scrapes too sharp nails across Shiro’s skin. He moves just enough to meet Shiro, to start hitting the knot that begins to swell. Keith doesn't spare a hand for his own cock, but thrusts it against Shiro's stomach with the movement.

“Keith, _baby,” _Shiro gasps it between kisses as he moves faster, as the edge gets nearer. “C-can I…?”

“_Please_,” Keith’s practically dropping on his cock now, the slick sound filthy and hypnotizing. It riles Shiro’s possessiveness, fills him with a ferocity he’s never felt before.

“_Mine_,” he hisses into the corner of Keith’s mouth. On the next down stroke they both push and the knot begins to stretch him.

“Yours,” Keith breathes, baring his throat. “Mark me, please— _Taka_—“

It destroys the last of Shiro’s doubts and second thoughts. He drags Keith’s throat to his mouth just as his knot begins to push in.

Keith makes a high noise and starts to come, his hole pulsing around the tightness of Shiro’s knot, cock spurting between them. It’s unbelievably good, the metal and Keith taste on his tongue as his teeth dig in, the rippling heat milking his cock.

He thrusts in the small space left to him, groaning at the feeling as he begins to come. It’s heavy and in his bones and he thrusts without thought, filling his omega, wallowing in the throbbing clutch and soft sounds the man is making. He’s never had a better orgasm, certain not a longer one. His cock is so deep, so hot--

The pleasure goes until he's emptied out. Mind placid, Shiro falls against the back of the couch. He keeps his omega clutched tight to his chest.

They both pant in the aftermath, adjusting slightly to keep the knot comfortable.

“Shiro?” The delicate way it’s said has Shiro opening his eyes to look at Keith. Keith who's propped himself up a little and it looking at Shiro so fondly.

Shiro’s still too punch drunk and Keith’s stunning. Before he knows it, he’s cupping the man’s cheek and pulling him in for a kiss.

Then Shiro tastes the blood, and he _remembers. _

“I bit you!” He says in quiet horror as he pulls his mouth away. His eyes go to Keith’s throat which looks like he was mauled by a small bear.

Keith’s thumb wipes at something on Shiro’s mouth and then pops it in his own. He looks impressively unconcerned. “Uh huh.” 

“And that’s… okay?” Shiro ventures, considering the cat-that-got-the-cream way Keith is looking at him.

“Now you’re getting it.”

Shiro can’t help but kiss him again.

After a few moments of lazy kisses he pulls back. “Still sorry though, your neck looks… bad.”

Keith nuzzles Shiro’s scent gland. “Don’t worry I think I’ve nearly matched you.”

And it does feel sore now that Keith’s mentioned it.

“So this is… a thing?”

“Well your knot is still stuffed inside me, so I certainly hope so.”

For some reason this makes Shiro blush. “You don’t have to say it like that.”

Keith laughs, dropping light kisses back up to Shiro’s mouth. “Is the big, brutish alpha feeling embarrassed now?” He pauses to look Shiro’s face over and then grins. “You are!”

It’s true enough. Shiro’s now just rolling back the tape in his head. He’d been rough and borderline possessive at the end. A little crazy from all the chemicals.

“I was just—“

Keith’s hand comes and covers his mouth. “You were just fine. You were just an alpha who had been baited by an omega and finally was given consent to act on it. It’s not deeper than that.” He pairs this with a meaningful look.

Slowly the hand peels away. “Baited?”

Keith’s smile then is coy with just an edge of something darker.

“Anyone ever tell you that you’re a little too honorable sometimes?”

It’s said with an edge of teasing, that would have Shiro tackling him down into the couch were they not still stuck. “You’re a brat,” Shiro says instead.

Keith leans close again, and there’s some give from below. Shiro’s knot is going down.

“Yeah?” Keith challenges, his lips just brushing Shiro’s, “What’re you going to do about it?”

**Author's Note:**

> This is for the lovely people on twitter who got real hype about a good!alpha Shiro thread I wrote. It's twice as long as it should be, but that's the sheith life. Comments fuel me in the cold dark nights of graduate school!
> 
> On twitter as @an_aphorism


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